摘  要：提出了一种高效的采用判决反馈算法的GMSK差分解调方法，该方法利用一种宽带的数字移相网络，对低通滤波器的输出信号进行正交变换，并采用软判决方法实现了判决反馈算法，它避免了原判决反馈算法中低通滤波器的延迟带来的性能恶化问题，且将判决反馈的运算量降低为原系统的一半，而对原算法的性能没有影响。该方法特别适合于手持跳频通信系统。从叠加了高斯噪声的两信号相位夹角概率分布出发，分析并导出了判决反馈算法的误码率计算公式。仿真结果表明，理论分析的误码性能和蒙特卡罗错误统计方法(Monte Carlo Error Counting Technique)的结果基本吻合。
关键词：判决反馈；GMSK；差分解调；误码率

Abstract: An efficient differential detection technique of GMSK system using decision feedback(DF) was proposed. This new method, by adding a broad band 90° phase-shift network after the LPF(Low Pass Filter) and a software decision method, presented the same performance as that of conventional DF detection system, but avoided the degradation in BER performance induced by the delay of LPF. The complexity of operation for the new DF system can be decreased as half the former system. This new method is especially useful for portable frequency hopping communication terminal. From the probability distribution of the phase angle between two vectors perturbed by Gaussian noises, the formulae of error probability performance of DF system were obtained. Simulation results show that the theoretical investigation gives analogous results with the Monte Carlo error counting technique.
Key words: decision feedback; GMSK; differential detection; error probability